cryogenic thermal insulation systems€¦ · systems are targeted for large-scale cryogenic...

Aug 2005 CryoTestLab 1

Cryogenic Thermal Insulation Systems

16th Thermal and Fluids Analysis WorkshopOrlando, FloridaAugust 9, 2005

James E. Fesmire

Stan D. Augustynowicz

Cryogenics Test Laboratory

NASA Kennedy Space Center


Outline

Introduction Part 1, MaterialsPart 2, TestingPart 3, ApplicationsConclusion

INTRODUCTION

HEAT IS THE ENEMY


Two things about cryogenics

Store a lot of stuff in a small spaceEnergy density

Use the cold temperature to do something useful

Refrigeration

Space launch and exploration is an energy intensive endeavor; cryogenics is an energy intensive discipline.


Cryogenics now touches on nearly every aspect of modern society

FoodHealth and medicineEnergyTransportationManufacturingResearchAerospace


Cryogenics on Earth and in space

Cryogens must be stored, handled, and transferred in safe and effective waysCryogenic usage and application is being extended to the rest of the world in the first half this centuryPeople working in cryogenics are becoming more and more specialized


For progress and efficiency into the 21st century, high performance thermal insulation systems are needed….


Energy Efficiency on EarthSpaceport facilities

Energy integrated launch sitePropulsion + Power + Life Support

Advanced transfer and storage methodsPropellants and gases productionNovel components and instrumentationNew material applicationsThermal insulation structures

Cost-efficient storage and transfer of cryogens


Energy Efficiency in Space

Space explorationIn-space depotsMoon baseMars baseOther destinations

Mass-efficient storage and transfer of cryogens


Energy Efficiency for Industry

IndustryHydrogen TransportationSuperconducting PowerProcesses & Applications


Thermal Insulation SystemsSystem Integrated Approach

Active + PassiveHot Side + Cold Side

Energy and Economics Perspective

Performance must justify the costSave $$ on energy bill

Two Things About InsulationConserve energy (or mass)Provide control of system

PART 1MATERIALS


BackgroundHistorical perspective

D’Arsonval in 1887 to Peterson in 1951WW II to H2 bomb to Apollo

Conventional materialsPerlite to multilayer to foam

Novel materialsAerogels to sol-gel aerogelsComposites old and composites new


Basics about Materials

Three Basic FormsBulk FillFoamsLayered

Basic Design FactorsDefinitions: k-value and CVP


Bulk-Fill Cryogenic Insulation Materials


New MaterialsCabot, aerogel beads (Nanogel®)Aspen Aerogels, aerogel blankets (Pyrogel® and Spaceloft®)Sordal, polyimide foams (SOLREX®)Inspec Foams, polyimide foams (SOLIMIDE®)TAI, pipe insulation panelsNASA, Layered Composite Insulation (LCI)


Performance

Price versus performance R5 or R1500, its your (extreme) choiceOverall Efficiency, four basic factors:

1. Thermal conductivity2. Vacuum level ($$$)3. System density or weight4. Cost of labor ($$) and materials ($)


1. Thermal ConductivityMaterial thermal conductivity

milliWatt per meter-Kelvin [mW/m-K]R-value per inch [hr-ft2-degF/Btu-in]1 mW/m-K = R144

Apparent thermal conductivityk-valueReal systems with large temperature differences

Overall k-value for actual field installationkoafiOften one order of magnitude (or more!) higher than reported ideal or laboratory k-values

Thermal Insulating Performance of Various Materials

0.01 0.1 1 10 100 1000 10000 100000 1000000

Pure Copper

Stainless Steel

Concrete

Whale Blubber

Ice

Oak Board

Cork

Fiberglass

Polyurethane Foam

Aerogel Composite Blanket

MLI System at SV

LCI System at SV

Aerogel Beads at HV

LCI System at HV

MLI System at HV

Thermal Conductivity (milliWatt per meter-Kelvin)

Representative k-valuesMaterial and Density HV

<10-4 torrSV

1 torrNV

760 torr

Vacuum, polished surfaces 0.5 to 5

Nitrogen gas at 200 K 18.7

Fiberglass, 16 kg/m3 2 14 22

PU foam, 32 kg/m3 21

Cellular glass foam, 128 kg/m3 33

Perlite powder, 128 kg/m3 1 16 32

Aerogel beads, 80 kg/m3 1.1 5.4 11

Aerogel composite blanket, 125 kg/m3 0.6 3.4 12

MLI, foil and paper, 60 layers, 79 kg/m3 0.09 10 ~24

New! LCI, 30 layers, 78 kg/m3 0.09 1.6 14

Boundary temperatures of approx. 293 K and 77 K; residual gas is nitrogen; k-value in mW/m-K.

Variation of k-value with cold vacuum pressure for glass bubbles in comparison with perlite powder and aerogel beads. Boundary temperatures are approximately 293 K and 77 K. Residual gas is nitrogen.

0.1

1

10

100

0.01 0.1 1 10 100 1000 10000 100000 1000000

C old V acuum Pressure C V P (m illitorr)

App

aren

t The

rmal

Con

duct

ivity

k-

valu

e (m

W/m

-K)

G lass B ubbles, C 137

Perlite Powder, 9 pcf

A erogel B eads, C 134

1

1 0

1 0 0

1 0 0 0

0 .1 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0C o ld V a c uum P ressure C V P (m illito rr)

Hea

t Flu

x (W

/m2)

and

Tot

al H

eat (

W)

H ea t F lu x , C 1 3 7

T ota l H ea t, C 1 3 7

Variation of mean heat flux and total heat transfer with cold vacuum pressure for glass bubbles. Boundary temperatures are approximately 293 K and 77 K. Residual gas is nitrogen.


2. Vacuum LevelSystem operating environment is Cold Vacuum Pressure (CVP)

High Vacuum (HV), below 10-4 torrSoft Vacuum (SV), from 1 to 10 torrNo Vacuum (NV), 760 torr

CVP is the first system design question and the primary cost driver for most applications


3. Density

Total installed density (or weight) is often critical for transportation applicationsDensity, as related to thermal mass, is also important for control of process systems


4. Cost

Performance must justify the costTotal heat flow, through insulation and all other sources, determines thermal performance requirementsManufacturing, maintenance, and reliability considerations are the key for determining overall cost

Aerogel Materials

LIGHTER THAN AIR?LIGHTER THAN AIR?


Aerogel Basics

World’s lightest solidLighter is not always betterSpecial class of open-pore structure nano-materials

Extremely low density (as low as several mg/cm3)High porosity (up to 99%)High surface area (over 1000 m2/g)Ultrafine pore size (as small as 2-nm radius)

Derived from the supercritical drying of highly cross-linked inorganic or organic gels

Sol-Gel processing methods

Flexible aerogel composite blanket, R&D 2003 Award winner, Aspen Aerogels and NASA-KSC

Commercial products, Aspen Aerogels, Inc.

Aerogel Composite Processing

Sol-Gel Process

catalyst catalyst

condensationhydrolysisSi(OEt)4 + nH2O + mEtOH Si(OH)4 + (m+n) EtOH SiO2 + 2H2O + (m+n) EtOH

← ←

Autoclave System

RADIATION SHIELDING: Aerogels produced in opacified [molecular sieve carbon (MSC)] fiber matrix for inhibition of radiation heat transfer in the infrared range

Aerogel Composite Heat Transfer

PORE SIZE

SURFACE AREA

PARTICLE LOADING

BULK DENSITYks

kg

kr

AEROGEL COMPOSITE CONCEPT:Use ultralow density aerogels formed within a fiber matrix to produce a flexible superinsulation

CORE OF THE TECHNOLOGY:Aerogels formed at the fiber-fiber contacts force solid heat transfer to occur through the very low thermal conductivity aerogels

CRYOGENIC-VACUUM INSULATION:Minimize heat transfer modes by designing insulation system for a given set of operating conditions

SolidConduction

GasConduction

kt = ks + kg + kr

∆T∆ Lq = kA

Total Radiation

SEM Micrographs of Aerogel/Fiber Composite

Aerogel Beads ProductionLarge-scale production by Cabot Corp. in 2003Economical precursor: sodium silicateBead formation using high throughput spray nozzleAerogel produced by low cost process with ambient pressure drying step

Waterglass Sol Hydrogel AerogelSilation

PART 2TESTING


Experimental Research TestingHeat transfer through insulation materials must be understood by testing under actual-use, cryogenic-vacuum conditionsTest methods and equipment Understanding test resultsAnalysis and modelingPerformance comparison of different materials


Comparison of Insulation Test Methods

Cryostats use steady-state liquid nitrogen boiloff calorimeter methodsDifferent methods and devices are complementary and necessaryNew Cryostat methods provide practical capability for testing real systems

Full temperature differenceFull-range vacuum conditions

Comparison of ASTM Methods and New Cryostat Methods

Method Type Sample Delta Temp

Boundary Temp Range (K)

k-value Range (mW/m-K)

Heat Flux Range (W/m2)

ASTM C518

Comparative, Heat Flow Meter

Flat, square Small 273 to 383 5 to 500 ---

ASTM C177

Absolute, Guarded Hot Plate

Flat, disk Small 93 to 773 14 to 2000 ---

ASTM C745

Absolute, Boiloff Calorimeter

Flat, disk Large 250/670 and 20/300

--- 0.3 to 30

Cryostat-1 Absolute, Boiloff Calorimeter

Cylindrical Large 77 to 300 0.03 to 30 0.8 to 120

Cryostat-2 Comparative, Boiloff Calorimeter

Cylindrical Large 77 to 350 0.1 to 50 2 to 400

Cryostat-4 Comparative, Boiloff Calorimeter

Flat, disk Large 77 to 350 0.5 to 80 6 to 900


Cryostat Test MethodsFull temperature difference ( T):

Cold-boundary temperature (CBT), 78 KWarm-boundary temperature (WBT), 300 KTemperature difference, 222 KMean temperature, 189 K

Full-range cold vacuum pressure (CVP):High vacuum (HV), below 1×10-4 torrSoft vacuum (SV), ~1 torrNo vacuum (NV), 760 torr


Description of CryostatsCryostat-1 and Cryostat-100

Cold mass 167 mm dia. by 900 mm length Test specimens up to 50 mm thickness

Cryostat-2Cold mass 132 mm dia. by 500 mm lengthTest specimens up to 50 mm thickness

Cryostat-4Test specimens 200 mm dia. by up to 30 mm thicknessCompressive load measurement (optional)

Cryostat-1

Cryostat-2

Cryostat-4

Example Test SeriesCryostat-1

Performance Characterization of Perforated MLI Blankets

Perforated multilayer insulation (MLI) blanket systems are targeted for large-scale cryogenic facilities. Space applications and particle accelerators are two fields concerned with thermal shielding of cryogenic devices. Because radiation heat transfer varies with T4, heat transfer in the range of 300K to 77K is dominant even for devices operating at temperatures as low as 2K. Systems operating under conditions of degraded vacuum levels are also a key consideration because of heat transfer by residual gas conduction. The results of an experimental study of a perforated MLI blanket system using a steady-state liquid nitrogen evaporation method are presented.

Experimental apparatus

Temperature and CVP ProfilesC135, 30 layers Jehier, 0.01µ

Test 1, Run 1, 09/04/01

50

100

150

200

250

300

350

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

time (h)

Tem

pera

tute

(K)

0.01

0.1

CV

P (m

icro

ns)

RTD1 RTD2 RTD3 RTD5 RTD6 RTD7 RTD8 RTD9RTD10 RTD11 RTD12 RTD13 RTD14 RTD15 RTD16 TC1TC2 TC3 TC4 TC5 TC6 TC7 TC8 CVP1

Liquid Nitrogen PressuresC135, 30 layers Jehier, 0.01m

Test 1, Run 1, 09/04/01

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

time (h)

Pres

sure

(ps

ig)

dP = P4 - P6

P3, Manifold

P5, Lower

P4, Upper

P6, Test

Measurements of Boil-off and k-value C135, 30 layers Jehier, 0.01m

Test 1, Run 1, 09/04/01

0

100

200

300

400

500

19 20 21 22 23 24 25 26 27

time (h)

Flow

(sc

m3 /m

in)

0.0

0.1

0.2

0.3

App

aren

t The

rmal

Con

duct

ivity

k (m

W/m

-K

Flow

k

Variation of k-value with cold vacuum pressure for different MLI

0.01

0.1

1

10

100

0.01 0.1 1 10 100 1000 10000 100000 1000000

Cold Vacuum Pressure (millitorr)

App

aren

t The

rmal

Con

duct

ivity

(mW

/m-K

Kaganer, MLI

C108, 40 layers MLI

C123, 60 layers MLI

C135, Perforated MLI Blanket

Layer temperature profiles as a function of blanket thickness

70

110

150

190

230

270

310

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0Thickness (mm)

Tem

pera

ture

(K)

0.011 millitorr, Test 10




1 millitorr, Test 3

5 millitorr, Test 9

10 millitorr, Test 4




Layer 0, CBT

Layer 2

Layer 1

Layer 30, WBT

Layer 20

Layer 15

Layer 5

Layer 10

PART 3APPLICATIONS


Main Categories

High Vacuum (HV)MLI or SI, microfiberglass, fine perlite, LCI, vacuum panels, aerogels

Soft Vacuum (SV)Aerogels, LCI, vacuum panels

No Vacuum (NV)Foams, cellular glass, fiberglass, aerogels


Examples

HV: LH2 storage tank, Fuel cell tanks, MLI blanket for Large Hadron Collider (LHC)SV: Piping connections, Mars surface storageNV: Shuttle External Tank, LO2 storage tank


New ApplicationsAerogel blankets for next-generation launch vehicle thermal protectionAerogel beads for cold box and non-vacuum applicationsLayered Composite Insulation (LCI), world’s lowest k-value system at soft vacuum levelGlass microspheres for cryogenic tanks and structural applicationsReusable polyimide foams for cryogenic tanks

CONCLUSION


There is a hot side and a cold side

The energy WILL balance.We want to make it balance to our best advantage.


Materials TestedLayered composite insulation (LCI)Aluminized Mylar and polyester fabricSyntactic foam compositesMicro fiberglassPerlite powderModular cryogenic insulation (MCI)Various composite insulation systemsPolystyreneAnd many others!

Multilayer insulation (MLI), various typesAluminum foil and fiberglass paperPolyester non-wovensPolyurethane foamAerogel powderAerogel beadsAerogel blanketsGlass microspheresPolyimide microspheresPolyimide foams


Research Testing Conclusion

Well over 1000 cryogenic thermal performance tests of over 100 different thermal insulation systems have been produced by the CryoTestLab at NASA Kennedy Space CenterSpecific insulation systems must be optimized for best performance (such as lowest k-value and bulk density) under different vacuum levelsAll modes of heat transfer (radiation, solid conduction, gas conduction, and convection) must be addressed


Significance and ImpactInvented new test equipment and methods for thermal performance characterization of insulation systemsNew standard for testing under actual-use, cryogenic-vacuum conditionsPartnered in development of new products now on the market

Aerogel composite blanket (Aspen Systems)Python vacuum-insulated piping (Chart-MVE)Aerogel beads for thermal insulation (Cabot)

Selected ReferencesFesmire, J. E. and Augustynowicz, S.D., “Improved Thermal-Insulation for Low Temperatures,”NASA Tech Briefs, September 2003, pp. 54-55.Fesmire, J.E., Augustynowicz, S.D., Heckle, K.W., and Scholtens, B.N., “Equipment and Methods for Cryogenic Thermal Insulation Testing,” Cryogenic Engineering Conference, 2003.Fesmire, J.E., and Augustynowicz, S.D, “Thermal Performance Testing of Glass Microspheres under Cryogenic-Vacuum Conditions,” Cryogenic Engineering Conference, 2003.Williams, M., Fesmire, J., Weiser, E., and Augustynowicz, S., “Thermal Conductivity of High Performance Polyimide Foams,” Cold Facts, Cryogenic Society of America, Spring 2002.Fesmire, J. E., Augustynowicz, S.D., and Darve, C., “Performance Characterization of Perforated MLI Blanket,” Proceedings of the Nineteenth International Cryogenic Engineering Conference, ICEC 19, Narosa Publishing House, New Delhi, 2003, pp. 843-846. Fesmire, J.E., Augustynowicz, S.D., and Rouanet, S., “Aerogel Beads as Cryogenic Thermal Insulation System,” in Advances in Cryogenic Engineering, Vol. 47, American Institute of Physics, New York, 2002, pp. 1541-1548.Fesmire, J.E., Augustynowicz, S.D. and Demko, J.A., “Thermal Insulation Performance of Flexible Piping for Use in HTS Power Cables”, in Advances in Cryogenic Engineering, Vol. 47, American Institute of Physics, New York, 2002, pp. 1525-1532.Augustynowicz, S.D. and Fesmire, J.E., “Cryogenic Insulation System for Soft Vacuum,” in Advances in Cryogenic Engineering, Vol. 45, Kluwer Academic/Plenum Publishers, New York, 2000, pp. 1691-1698. Augustynowicz, S.D., Fesmire, J.E., and Wikstrom, J.P., “Cryogenic Insulation Systems,” in 20th

International Congress of Refrigeration Sydney, no. 2000-1147, International Institute of Refrigeration, Paris, 2000. Fesmire, J.E., Rouanet, S., and Ryu, J., “Aerogel-Based Cryogenic Superinsulation,” in Advances in Cryogenic Engineering, Vol. 44, Plenum Press, New York, 1998, pp. 219-226.

CHURCHILL’S COMMENTARY ON MAN:Man will occasionally stumble overthe truth, but most of the time he willpick himself up and continue on

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